Authentication, input and response

Headers

Name	Type	Description
Content-Type	string	application/json
x-api-key*	string	Unique API key from Altum. Obtain one via Mopsus (https://mopsus.altum.ai)

This is the main endpoint of the API. It retrieves a list of subsidies based on a user's postcode and, if provided, their personal and financial details for loan eligibility checking.

GET: https://api.altum.ai/market-trend

Request body

Market Trend Request Model

Field	Type	Description
postcode*	string	Required. The Dutch postcode (e.g., "3511 AA").

Example Complete Input

A valid GET Request body would look like this:

{"postcode": "5258BA"}

Upon a successful POST request, the API returns a 200 OK status with a JSON object containing the results.

Market Trend API Response Model

Field	Type	Description
postcode	String	The normalized Dutch postcode (e.g., "1011AB") used for the query.
city	String	The city name derived from the master address database.
neighbourhood	String	The specific neighborhood name (if available in Dataland source).
municipality	String	The administrative municipality governing the area.
averagePriceSingleFamilyHomes	Float	The average transaction price for single-family properties (detached, semi-detached, terraced).
averagePriceMultiFamilyHomes	Float	The average transaction price for multi-family properties (apartments/flats).
pricePerSquareMeterSingleFamily	Float	The average price per square meter (€/m²) for single-family homes.
pricePerSquareMeterMultiFamily	Float	The average price per square meter (€/m²) for apartments.
annualPriceChange	Float	The annualized percentage growth (CAGR) of property values compared to the previous recorded year.
fiveYearPriceChange	Float	The projected percentage change in value over a 5-year period based on historical growth trends.
totalSalesLast12Months	Integer	The total count of property transactions recorded in this postcode over the last 365 days.
priceDistribution	Object	A dictionary serving as a histogram, mapping price ranges (e.g., "250-500k") to the number of properties sold in that bracket.
pricePerSquareMeterDistribution	Object	A dictionary serving as a histogram, mapping price-per-m² ranges (e.g., "3000-3500") to the frequency of sales in that bracket.

Output

Upon a successful GET request, the API returns a 200 OK status with a JSON object containing the results.

Example Complete Output

{
  "region": {
    "postcode": "5258BB",
    "city": "BERLICUM NB",
    "neighbourhood": "Berlicum",
    "municipality": "Sint-Michielsgestel"
  },
  "averagePriceSingleFamilyHomes": 681870.58,
  "averagePriceMultiFamilyHomes": null,
  "pricePerSquareMeterSingleFamily": 1035.61,
  "pricePerSquareMeterMultiFamily": null,
  "annualPriceChange": 6.67,
  "fiveYearPriceChange": 38.09,
  "transactionData": {
    "totalSalesLast12Months": 0
  },
  "priceDistribution": {
    "250-500k": 2,
    "500-750k": 4,
    "1M+": 2
  },
  "pricePerSquareMeterDistribution": {
    "0-2500": 8
  }
}

Explanation

🏘️ Region

"region": {
  "postcode": "5258BB",
  "city": "BERLICUM NB",
  "neighbourhood": "Berlicum",
  "municipality": "Sint-Michielsgestel"
}

All the data and KPIs are calculated for postcode 5258BB, providing context at the city BERLICUM NB, neighborhood Berlicum, and municipality Sint-Michielsgestel.

💰 Average Property Prices

"averagePriceSingleFamilyHomes": 681870.58,
"averagePriceMultiFamilyHomes": null

• Single-family homes: €681,870 on average.

• Multi-family homes / apartments: No data available for this area.

This tells us that houses in this postcode are relatively expensive, and the market for apartments is either very small or not recorded.

📏 Price Per Square Meter

"pricePerSquareMeterSingleFamily": 1035.61,
"pricePerSquareMeterMultiFamily": null

• Single-family homes: €1,035 per m².

• Multi-family homes: No data available.

This gives a way to compare house prices fairly, even if the sizes of the houses differ.

📈 Price Trends

"annualPriceChange": 6.67,
"fiveYearPriceChange": 38.09

• Annual price change: +6.7% → prices increased over the last year.

• Five-year price change: +38.1% → prices increased significantly over the last 5 years.

This shows that house prices are rising in both the short term and long term.

🏷️ Transaction Activity

"transactionData": {
  "totalSalesLast12Months": 0
}

• Number of sales in the last 12 months: 0

This means no houses were sold in this area over the past year, so the market is currently inactive.

💵 Price Distribution

"transactionData": {
  "totalSalesLast12Months": 0
}

• How many houses were sold in each price range (all-time, not just last 12 months):

  • €250k–€500k → 2 houses

  • €500k–€750k → 4 houses

  • €1M+ → 2 houses

  Most houses sold in this postcode fall in the €500k–€750k range, with a few high-end sales over €1M.

🏠 Price Per Square Meter Distribution

"pricePerSquareMeterDistribution": {
  "0-2500": 8
}

• All 8 recorded sales are in the 0–2,500 €/m² range.

This tells us that even expensive houses are relatively modest in €/m² compared to very high-end markets.

200: OK Standard response

Request processed and data returned.

400: Bad Request Unsuccessful response

404 Not Found

422 Validation Error

500: Internal Server Error Service is not available and/or down